Apparatus and method for producing a high degree of twist in yarn

ABSTRACT

Yarn texture is imparted with a high degree of twist, and at a high speed, to a continuous multifilament yarn; a low friction anvil member is spaced closely from a mating movable friction member. They thus form a barrier through which the yarn to be twisted cannot pass. The yarn is urged toward the barrier and toward the moving friction surface. High twist levels are attained by not only contacting the yarn with the moving friction surface but by wrapping it partially around such surface.

United States Patent Sholly, Jr. et al.

[54] APPARATUS AND METHOD FOR PRODUCING A HIGH DEGREE O TWIST IN YARN Y lnventors: William C. Sholly, Jr., Souderton,

Pa.;' George A. Carruthers, Lancaster, England .Turbo Machine Company, Lansdale,

Filed: May 20, 1971 Appl. No.: 145,326

Assignee:

References Cited UNITED STATES PATENTS I 3,345,811 10/1967 Gilchrist..... 57777.45

us. c1 .;.....s7/77.4 1m. c1. ..D02g 1 1 04, D0lh 7/92- Field of Search ..s7/77.3-77.45

[ 1 Dec. 12, 1972 Tully ..57/77.4 McIntosh ..57/77.4

' Primary Examiner-Donald E. Watkins Attorney-Paul & Paul 57 ABSTRACT Yarn texture is imparted with a high degree of twist, and at a high speed, to a continuous multifilament yarn; a low friction'anvil member is spaced closely from a mating movable friction member. They thus form a barrier through which the yarn to betwisted cannot pass. The yarn is urged toward the barrier and toward the moving friction surface. High twist levels are attained by not only contacting the yarn with the moving friction surface but by wrapping it partially around such surface.

' 11 Claims, 6 Drawing Figures PATE NT'ED um 12 I972 SHEET 1 BF 2 .IIIIII.

III IIlI S m mum O1U S T U U mwwfim n MSW w CA A me mm m W Y B PATENTEDHEI: 12 m2 3; 705488 SHEET 2 0F 2 I ENTORS. William C. olly,Jr.

By George Alon Corruthers ATTORNEYS.

APPARATUS AND METHOD FOR PRODUCING A HIGH DEGREE OF TWIST IN YARN This invention pertains to'a deviceand method for imparting false twist to a continuous multifilament yarn with'a high degree of efficiency and with high yarn speed. More specifically, it pertains to an improved friction twister of the type wherein a movable friction member is'spaced from a mating anvil member to form a narrow barrier toward which the yarn is urged and adjacent'which the yarn is engaged by the friction surface to impart a twist thereto, and wherein the yarn is wrapped at least partially around the friction surface. The enhanced efficiency attained by urging the yarn toward and around the friction surface is the primary novel feature of the present invention. In the preferred embodiment, yarn is passed through a plurality (three, for example) of successive pairs of friction surfaces and anvils all of which are rotatable and which are mounted on parallel shafts. One shaftiincludes two wheel-like members, with hard rubber rings as. the friction surfaces on the outer circumferences thereof, with a lesser radius rotating anvil member therebetween. The other shaft includes two rotating anvil members similar to that on the first shaft with a friction member, also similar .to the two friction members on the first shaft therebetween. Preferably, the yarn path entering and leaving the second of the three successive friction member-anvil member pairs forms an angle in the place which includes the yarn path of from 60 l7O.

Numerous methods and types of apparatus have been proposed and developed for imparting false twist to continuous multifilament yarn. One common type of commercially available false twisting apparatus utilizes a spindle' about which the yarn is wrapped. The spindle of such apparatus makes one revolution for each turn of twist placed in the yarn. Physical limitations on the speed with which the spindle can be turned therefore limit the speed of the false twisting operation and ultimately limit production thereof.

Another prior art false twisting method is that which may be generally referred to as friction twisting. In the more common types of friction twisting, yarn is passed over the outer edge of a rotating friction surface or over the inner-edge of an annular friction surface. The false twist produced in devices of this type tends to be highly erratic due primarily to migration of the yarn path on the friction surface.

A particularly promising type of friction twister is that disclosed and claimed in the U. S. application of George A. Carruthers, Ser. No. 45,11l, filed June 10, I970. ln that invention, continuous multifilament yarn is twisted by passing the yarn substantially tangentially against a movable friction surface. Movement of the friction surface twists the frictionally engaged yarn by exerting a torque force thereon. However, there is a limit to the degree of twist that is commercially obtainable using such a machine. It is an important object of this invention to obtain a significantly higher degree of twist.

More specifically,it is an object of the present invention to provide an improved false twist device and method wherein yarn is engaged by mating friction and low friction surfaces at exceedingly high yarn speeds and in which high rates of twist per inch are attainable.

These and other objects which will be apparent in the course of the subsequent discussion, are met by the present invention which comprises, briefly, a low friction anvil member together with a movable friction surface which is shaped as an edge or as a sharp curvature. As in the Carruthers application, the anvil and the friction edge define a barrier and a confined region adjacent thereto, the movable friction surface moving away from the barrier near the confined region. Means are provided for passing yarn past this confined region and biasing the yarn toward the barrier and perpendicularly toward the friction surface where it engages the yarn. It is the latter'factor, causing engagement of the yarn with the edge of the friction surface, which has been found to produce the greatly enhanced twisting effectiveness of the present invention.

In one preferred form of the present invention, the low friction member and the friction surface means rotate about parallel axes and preferably at least three such sets of rotating friction members and low friction members act'on the yarn in sequence, with yarn path deviation for each set. In this embodiment, each friction member is immediately adjacent, along its axis, a low friction member and vice versa. All friction members are desirably of equal radius as are all low friction members, the formerbeing larger than the latter. The friction members are all commonly driven by frictional engagement with a cylindrical driving means.

Preferably also, the friction members are wheel-like members with rings at the outer circumference thereof so that the curvature of the outer circumference toward the axis of the rotating friction member prevents excessive wear at the edges of the friction surface by the yarn and nevertheless provides the edge contact that is so important according to this invention.

This invention may be better understood by reference to the following detailed description, taken in conjunction with the appended claims and the accompanying drawings, in which:

FIG. 1 is a schematic illustration of one station of a multi-unit false twisting apparatus, as may be used in commercial production, in which is incorporated one embodiment of the false twisting device of the present invention;

FIG. 2 is an enlarged top view of the false twisting device shown in FIG. 1;

FIG. 3 is a front view of the device shown in FIG. 2;

FIG. 4 is a side section view of the device shown in FIG. 3;

FIG. 5 is a sectioned detail view of a part of the device shown in FIG. 2; and

FIG. 6 is an enlarged detailed view of a portion of the device shown in FIG. 4.

Referring more specifically to FIG. 1, there is shown a false twisting apparatus including yarn 4 which runs under tension from supply bobbin 2 through twist trap 6, guides 8, l0 and 12, tension device 14 and heating zone 16. Yarn 2 is trained helically around a copper pipe (not shown) having steam therein. The length of heating zone 16, the number of wraps which yarn 2 takes about the heating unit therein and the heat level in the heater of zone 16 may be varied depending on yarn composition, yarn denier, yarn feed rate, etc.

Before entering heating zone 16 yarn 2 passes over a deep V groove pulley.

Upon leaving heating zone 16, yarn 2 passes over non-twist trapping guides 20, 22, 24, 26, 28 and 30 before entering false twist device 32 of the present invention, driven frictionally by cylindrical driving member 34. Leaving false twist device 32, yarn 2 passes through guides 36 and 38 to. yarn detector 40 which controls trapper 6. Yarn 2 then passes through guide 42, tensioning device 44, guides 46 and 48 and onto takeup package 50. It will be noted that guide 48 is a traversing guide, as indicated by a double headed arrow in FIG. 1, to control the disposition of yarn 2 on takeup package 50.

It will also be noted that the apparatus schematically illustrated in FIG. 1 may comprise a single unit or station of a multi-unit machine. Thus yarn 2a and yarn trapper 40a of an adjacent station is shown in phantom lines on the left of the apparatus shown in FIG. 1 and yarn 2a, heating zone 16a, and guides 20a and 22a for the work station to the right of that shown in FIG. 1 are also shown in phantom lines. Common shaft 52 drives cylindrical driving member 34 and extends to adjacent work stations for driving cylindrical driving members thereof. Shaft 52 is in turn driven by belt 54.

Some means, not shown, may also be provided to disengage cylindrical driving member 34 from false twist device 32.

As shown in FIG. 1, and as may be more clearly seen in FIGS. 2, 3 and 5, guides 30 and 36 are positioned so as to bias yarn 2, as it enters and leaves false twist device 32, upwardly and forwardly i.e., downward in the enlarged plan detailed view of FIG. 2. The purpose and importance of this biasing will be made more apparent hereinafter.

Referring now to FIGS. 2 and 3, in which false twist device 32 of FIG. 1 may be seen in more detail, there is shown a plurality of movable, more specifically, rotatable, friction members 56, all of equal radius and all driven by frictional engagement with common driving member 34. Opposing each of the friction members 56 is a low friction surface 'means, more specifically smooth, hard cylindrical rotating anvil members 58, all of equal radius also but smaller than friction members 56. In this the preferred embodiment of the present invention, friction members 56 and anvil members 58 are disposed alternately on two parallel shafts 60.

Preferably, each friction member 56 comprises, as seen more clearly in FIG. 5, a wheel-like member 56a having disposed at its outer circumferential edge, a hard rubber, such as polyurethane or Buna-N synthetic rubber, O ring 5612 to provide the friction surface which engages yarn 2.

As is seen more clearly in FIG. 4, anvil members 56 are freely turnable on shafts 60.

As seen in the enlarged view of FIG. 6, each of the friction members 56 together with its mating anvil member 58 defines a barrier 62 and a confined region 64 adjacent thereto. Biasing yarn 2 toward barrier 62 while passing it through confined region 64 causes frictional engagement of yarn 2 with moving friction member 56 producing a torque effect on yarn 2 and ultimately false twisting thereof. The surface of friction member 56 moves away from the barrier 62 in the area of confined region 64. By virtue of the frictional engagement of friction member 56 with yarn 2, this tends to prevent yarn 2 from being squeezed, as a result of the tension in yarn 2, into barrier 62. It also provides a self-compensating effect in that if yarn 2 migrates for any reason toward barrier 62 the frictional engagement of friction member 56 with yarn 2 increases and friction member 56 drags the path of yarn away from barrier 62.

Asseen in FIG. 3, yarn 2 passes under the barrier of the first set of friction members 56 and anvil member 58, over the second such barrier and under the third such barrier, thus being tensioned in each case toward the barrier.

Due to their relative positions, spacing and radii of successive friction members 56 anvil members 58 sets, barriers 62 of each of these sets are horizontally offset. The much enhanced twisting effectiveness of the twist device of the present invention results from guiding yarn 2 so that the yarn path is angled toward the axis of friction member 56 as yarn 2passes through the confined region 64 adjacent thereto; the yarn wraps around a portion of the friction surface. More specifically, yarn 2 is biased substantially perpendicularly toward the friction surface of friction members 56 in those areas where yarn 2 is engaged by friction membars 56. This produces frictional engagement of yarn at the edges of each of the friction members 56.

To prevent excessive wear on the edges of friction members 56, friction members 56 on their outer edges are preferably relieved or curved toward their respective axes. The utilization of O-rings 56b to provide the friction surfaces on friction members 56 is a practical and useful expedient by which this curvature is inherently provided.

To a large extent, the degree of effectiveness with which twist is imparted to the yarn, as it passes between a friction member and mating anvil member in accordance with the present invention, is governed by the degree of wrapping of the yarn around the friction member, or the angling of the yarn path perpendicularly toward the engaging surface of the friction member. For example, in the preferred embodiment of the present invention, as shown in FIGS. 1 6, the angle [3 formed by yarn 2 in the plane which includes the path of yarn 2 as yarn 2 enters and leaves a specific twisting region, as shown specifically in FIG. 5, is about 140. Generally, this angle is in the range of about 60 to 170. Angles in the lower part of this range are preferred. At these angles, using denier 34 filament nylon running at 625 feet per minute with a tension of 28 grams in the yarn entering the device and a tension of 71 grams in the yarn leaving the device and with Buna-N synthetic rubber O-rings as the friction surfaces of friction members 56, 97 twists per inch has been imparted with an angle of beta of 82 twists per inch have been imparted with an angle of l58. It will be noted that these twists per inch measurements are all comparable to or above those produced in current commercial operations and that these twist rates have been produced at yarn running speed substantially in excess of those of which spindle type false twisting devices are capable. In other tests, utilizing denier polyester in the preferred embodiment of the present invention, yarn running rates of 1,250 feet per minute have been attained.

By way of summary, in the method of the present invention, continuous multifilament yarn is passed through the confined region adjacent the barrier formed by a low friction anvil surface and a mating movable friction surface moving a direction adjacent said confined region away from said barrier while the yarn passing through the confined region is deflected away from a straight line path and toward'the barrier and substantially perpendicularly toward the friction surfacein the area of engagement. The yarn may be passed sequentially through two or more of such confined regions, and angled or wrapped as discussed I. In a yarn false twisting apparatiis comprising a movable member having a friction surface, anvil means providing a low friction surface adjacent said friction surface and positioned so closely as to form a barrier therebetween, through which said yarn does not pass, said friction surface having an edge portion extending toward said yarn, and yarn feeding and guide means arranged for continuously urging said yarn toward and I into frictional engagement with said friction surface,

and wrapping at least partially around said edge portion.

2. The apparatus defined in claim 1, wherein said edge portion is at least partially curved.

3. A yarn false twisting apparatus as recited in claim 1, wherein said movable member has a circumferential friction surface curved at its edge toward the axis of said friction member.

4. An improved yarn false twisting device, as recited in claim 3, wherein said anvil means is freely rotatable and has an axis parallel with that of said rotatable friction member.

5. An improved yarn false twisting device, as recited in claim 4, wherein said anvil has a hard, flat, smooth outer circumferential surface.

6. An improved yarn false twisting device, as recited in claim 4, wherein the yarn paths entering and leaving said barrier are at an angle of from about 60 to 170.

7. An improved yarn false twisting device, as recited in claim 4, wherein said movable member having a friction surface comprises a wheel with a circumferential frictional ring.

8. An improved yarn false twisting device, as recited in claim 4, wherein a plurality sets of said rotating friction members with friction surfaces and adjacent low friction surface means are disposed adjacent one another on two common axes, friction members and low'friction surface means being immediately adjacent recited in claim 9, wherein said friction members are rotated by frictional engagement with a cylindrical drivin means.

l1. alse twist apparatus defined m claim 1, wherein said guide means is arranged to cause the yarn to wrap not only from side to side around said edge, but up and down as well. 

1. In a yarn false twisting apparatus comprising a movable member having a friction surface, anvil means providing a low friction surface adjacent said friction surface and positioned so closely as to form a barrier therebetween, through which said yarn does not pass, said friction surface having an edge portion extending toward said yarn, and yarn feeding and guide means arranged for continuously urging said yarn toward and into frictional engagement with said friction surfaCe, and wrapping at least partially around said edge portion.
 2. The apparatus defined in claim 1, wherein said edge portion is at least partially curved.
 3. A yarn false twisting apparatus as recited in claim 1, wherein said movable member has a circumferential friction surface curved at its edge toward the axis of said friction member.
 4. An improved yarn false twisting device, as recited in claim 3, wherein said anvil means is freely rotatable and has an axis parallel with that of said rotatable friction member.
 5. An improved yarn false twisting device, as recited in claim 4, wherein said anvil has a hard, flat, smooth outer circumferential surface.
 6. An improved yarn false twisting device, as recited in claim 4, wherein the yarn paths entering and leaving said barrier are at an angle of from about 60* to 170*.
 7. An improved yarn false twisting device, as recited in claim 4, wherein said movable member having a friction surface comprises a wheel with a circumferential frictional ring.
 8. An improved yarn false twisting device, as recited in claim 4, wherein a plurality sets of said rotating friction members with friction surfaces and adjacent low friction surface means are disposed adjacent one another on two common axes, friction members and low friction surface means being immediately adjacent one another on each of said axes, each of said friction members having a radius larger than that of at least one of said low friction surface means immediately adjacent thereto.
 9. An improved yarn false twisting device, as recited in claim 8, wherein all of said friction members are of substantially equal radius.
 10. An improved yarn false twisting device, as recited in claim 9, wherein said friction members are rotated by frictional engagement with a cylindrical driving means.
 11. False twist apparatus defined in claim 1, wherein said guide means is arranged to cause the yarn to wrap not only from side to side around said edge, but up and down as well. 